P0037: HO2S Heater Control Circuit Low (Bank 1, Sensor 2)

P0037: HO2S Heater Control Circuit Low (Bank 1, Sensor 2)

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P0037: Low HO2S Heater Control Circuit? Here’s What You Need to Know

Look - if you're dealing with OBD2 code P0037, it means your Bank 1 Sensor 2 heated oxygen sensor (HO2S) is having trouble getting the current it needs. This doesn't mean the sensor itself is necessarily bad, but the circuit controlling its heater is acting up. It’s critical because this can affect your engine performance and emissions.

This issue usually points to either a wiring problem, a blown fuse, or a failed sensor. If you ignore it, you might face poor fuel economy or increased emissions, which can lead to more significant problems down the line. So, let’s nail down the symptoms and diagnostics so you can tackle this head-on.

Symptoms

  • Check Engine Light illuminated
  • Poor fuel economy
  • Rough idling
  • Increased emissions
  • Failed emissions test
  • Erratic engine performance
  • Excessive exhaust smoke
  • Heater circuit fault code on scan tool

Diagnostic order

  1. Check the fuse for the oxygen sensor heater circuit (typically 10-15A).
  2. Inspect wiring and connectors for damage or corrosion; look for resistance above 3 ohms.
  3. Measure the voltage at the sensor heater terminal; it should be around 12V with the engine running.
  4. Test the sensor itself for proper operation; a healthy sensor should show resistance between 10-30 ohms for the heater circuit.
  5. If all else checks out, consider replacing the sensor, which usually runs around $50-$150.

Common questions

What does P0037 mean?

P0037 indicates a low voltage in the heater control circuit of the oxygen sensor, specifically Bank 1, Sensor 2.

Can I drive with P0037?

While you can drive, it’s not recommended as it can lead to poor fuel efficiency and increased emissions.

How do I fix code P0037?

Start with checking the fuse and wiring. If those are fine, test the oxygen sensor, and replace if needed.

What is the cost to fix P0037?

Fixing P0037 can range from $50 for a fuse or wiring repair to $150 or more for a new sensor.

Will P0037 affect performance?

Yes, it can lead to rough idling and poor engine performance due to incorrect air-fuel mixture readings.

How often does P0037 occur?

This code is not uncommon, especially in vehicles over 100,000 miles or those with exposed wiring.

Can I reset the check engine light after fixing P0037?

Yes, after repairs, you can reset the light using an OBD2 scanner or by disconnecting the battery for a few minutes.

Are there any recalls related to P0037?

Check with your dealer for any recalls specific to your vehicle - some manufacturers may have known issues.

Vehicle-specific notes

  • Ford EcoBoost engines may have harness issues near the turbo that affect sensor readings.
  • Honda K-series often suffers from wiring corrosion due to heat and moisture.
  • Toyota 2GR-FE V6 models can have faulty sensors if they are over 100,000 miles.
  • GM 2.4 Ecotec engines frequently experience harness damage from engine movement.
  • Chrysler 3.6 Pentastar engines have been known to throw P0037 after a battery replacement.
  • Subaru EJ20 often shows this code after exhaust modifications or sensor replacements.
  • BMW N20/N54/N55 engines may require software updates to address sensor issues.
  • Hyundai/Kia Theta II engines have some known issues with the sensor connectors becoming loose.
  • Ram Cummins 6.7L diesel engines might show this code due to sensor location near high heat areas.
  • GM Duramax engines may have issues with the heater circuit from wear and tear over time.

Parts and cost ranges

  • Oxygen Sensor: $50 - $150
  • Wiring Harness: $30 - $100
  • Fuse: $5 - $15
  • Diagnostic Scan Tool: $50 - $200 (if needed)
  • Labor Costs: $75 - $150 per hour

What people get wrong

  • Replacing the sensor without checking the wiring first.
  • Assuming the sensor is bad without proper testing.
  • Ignoring the fuse status during diagnostics.
  • Not addressing potential water intrusion issues in the connectors.
  • Overlooking software updates for certain makes and models.

Related codes

If you're dealing with P0037, you might also want to check out P0036 or P0135 for further insights into oxygen sensor and heater circuit issues.

Stop throwing parts at your car. The Mobile Master Mechanic app walks you through the exact diagnostic for YOUR specific VIN - engine, year, trim, even mileage-specific known issues. Free download.

-- Hank, Master Mechanic at Mobile Master Mechanic

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